Henry Havelock Ellis
1859 – 1939
Henry Havelock Ellis was a British physician, psychologist, writer, and social reformer who studied human sexuality, as well as publishing works on transgender psychology. In 1913 Ellis proposed the term sexo-aesthetic inversion to describe what is now called transgender phenomenon. In 1920 he coined the term eonism, which he derived from the name of a historical figure, Chevalier d'Eon.